Audio LecturePro Feature Flexor Pollicis Longus 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x The flexor pollicis longus is a muscle within the deep compartment of the anterior forearm. Attachments: Originates from the anterior surface of the radius and surrounding interosseous membrane. The tendon passes through the carpal tunnel and attaches to the base of the distal phalanx of the thumb. Actions: Flexes the interphalangeal joint and metacarpophalangeal joint of the thumb. Innervation: Median nerve (anterior interosseous branch). Blood supply: Ulnar artery By TeachMeSeries Ltd (2026) Fig 1Deep flexor muscles of the anterior forearm. 3D ModelPro Feature You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Dissection AtlasPro Feature Prosection of the deep compartment of the anterior forearm, with the superficial muscles divided and reflected. Prosection of the deep compartment of the anterior forearm, with the superficial muscles divided and reflected. You've Discovered a Pro Feature Access our Dissection Image Library Enhance your understanding with high-resolution dissection images showcasing real-life anatomy. Learn More In gratitude to our body donorsLearn more In gratitude to our body donors We are deeply grateful to the individuals who chose to donate their bodies for the advancement of medical education. Their generosity makes these images possible and provides students and healthcare professionals with an invaluable opportunity to study human anatomy. We recognise the profound contribution made by each donor and their families, and we use these images with the dignity and respect their gift deserves. Acknowledge Frequent questions What is the function of the flexor pollicis longus muscle? The flexor pollicis longus muscle primarily flexes the interphalangeal and metacarpophalangeal joints of the thumb. This action is crucial for thumb movements, enabling grip and pinching. Where does the flexor pollicis longus originate? This muscle originates from the anterior surface of the radius and the adjacent interosseous membrane. Its unique positioning allows it to effectively contribute to thumb flexion. How is the flexor pollicis longus innervated? The flexor pollicis longus is innervated by the median nerve, specifically through its anterior interosseous branch. This nerve supply is vital for the muscle's function and coordination. What are the attachments of the flexor pollicis longus tendon? The tendon of the flexor pollicis longus passes through the carpal tunnel and attaches to the base of the distal phalanx of the thumb. This specific attachment point facilitates thumb flexion. Which arteries supply blood to the flexor pollicis longus? The blood supply to the flexor pollicis longus muscle comes primarily from the ulnar artery. Adequate blood flow is essential for the muscle's health and functionality. Rate This Article